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121.
Ligia Rebelo Gomes John Nicolson Low Ana S. M. C. Rodrigues James L. Wardell Marcus V. N. de Souza Thais C. M. Noguiera Alessandra C. Pinheiro 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(8):920-926
(E)‐2‐(2‐Benzylidenehydrazinylidene)quinoxaline, C15H12N4, crystallized with two molecules in the asymmetric unit. The structures of six halogen derivatives of this compound were also investigated: (E)‐2‐[2‐(2‐chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)‐2‐[2‐(3‐chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)‐2‐[2‐(4‐chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)‐2‐[2‐(2‐bromobenzylidene)hydrazinylidene]quinoxaline, C15H11BrN4; (E)‐2‐[2‐(3‐bromobenzylidene)hydrazinylidene]quinoxaline, C15H11BrN4; (E)‐2‐[2‐(4‐bromobenzylidene)hydrazinylidene]quinoxaline, C15H11BrN4. The 3‐Cl and 3‐Br compounds are isomorphous, as are the 4‐Cl and 4‐Br compounds. In all of these compounds, it was found that the supramolecular structures are governed by similar predominant patterns, viz. strong intermolecular N—H...N(pyrazine) hydrogen bonds supplemented by weak C—H...N(pyrazine) hydrogen‐bond interactions in the 2‐ and 3‐halo compounds and by C—H...Cl/Br interactions in the 4‐halo compounds. In all compounds, there are π–π stacking interactions. 相似文献
122.
Daniela Pinheiro Gaspar Gilson Celso Albuquerque Chagas Junior Eloisa Helena de Aguiar Andrade Lidiane Diniz do Nascimento Renan Campos Chist Nelson Rosa Ferreira Luiza Helena da Silva Martins Alessandra Santos Lopes 《Molecules (Basel, Switzerland)》2021,26(13)
In addition to the vast diversity of fauna and flora, the Brazilian Amazon has different climatic periods characterized by periods with greater and lesser rainfall. The main objective of this research was to verify the influence of climatic seasons in the Brazilian Amazon (northeast of Pará state) concerning the aromatic and bioactive profiles of fermented and dried cocoa seeds. About 200 kg of seeds was fermented using specific protocols of local producers. Physicochemical analyzes (total titratable acidity, pH, total phenolic compounds, quantification of monomeric phenolics and methylxanthines) and volatile compounds by GC-MS were carried out. We observed that: in the summer, the highest levels of aldehydes were identified, such as benzaldehyde (6.34%) and phenylacetaldehyde (36.73%), related to the fermented cocoa and honey aromas, respectively; and a total of 27.89% of this same class was identified during winter. There were significant differences (p ≤ 0.05, Tukey test) in the profile of bioactive compounds (catechin, epicatechin, caffeine, and theobromine), being higher in fermented almonds in winter. This study indicates that the climatic seasons in the Amazon affect the aromatic and bioactive profiles and could produce a new identity standard (summer and winter Amazon) for the cocoa almonds and their products. 相似文献
123.
A new model is proposed to a collapsing star consisting of an initial inhomogeneous energy density and anisotropic pressure
fluid with shear, radial heat flow and outgoing radiation. In previous papers one of us has always assumed an initial star
with homogeneous energy density. The aim of this work is to generalize the previous models by introducing an initial inhomogeneous
energy density and compare it to the initial homogeneous energy density collapse model. We will show the differences between
these models in the evolution of all physical quantities that characterizes the gravitational collapse. The behavior of the
energy density, pressure, mass, luminosity and the effective adiabatic index is analyzed. The pressure of the star, at the
beginning of the collapse, is isotropic but due to the presence of the shear the pressure becomes more and more anisotropic.
The black hole is never formed because the apparent horizon formation condition is never satisfied, in contrast of the previous
model where a black hole is formed. An observer at infinity sees a radial point source radiating exponentially until reaches
the time of maximum luminosity and suddenly the star turns off. In contrast of the former model where the luminosity also
increases exponentially, reaching a maximum and after it decreases until the formation of the black hole. The effective adiabatic
index is always positive without any discontinuity in contrast of the former model where there is a discontinuity around the
time of maximum luminosity. The collapse is about three thousand times slower than in the case where the energy density is
initially homogeneous. 相似文献
124.
125.
Brígida AI Pinheiro AD Ferreira AL Gonçalves LR 《Applied biochemistry and biotechnology》2008,146(1-3):173-187
An agroindustrial residue, green coconut fiber, was evaluated as support for immobilization of Candida antarctica type B (CALB) lipase by physical adsorption. The influence of several parameters, such as contact time, amount of enzyme
offered to immobilization, and pH of lipase solution was analyzed to select a suitable immobilization protocol. Kinetic constants
of soluble and immobilized lipases were assayed. Thermal and operational stability of the immobilized enzyme, obtained after
2 h of contact between coconut fiber and enzyme solution, containing 40 U/ml in 25 mM sodium phosphate buffer pH 7, were determined.
CALB immobilization by adsorption on coconut fiber promoted an increase in thermal stability at 50 and 60 °C, as half-lives
(t
1/2) of the immobilized enzyme were, respectively, 2- and 92-fold higher than the ones for soluble enzyme. Furthermore, operational
stabilities of methyl butyrate hydrolysis and butyl butyrate synthesis were evaluated. After the third cycle of methyl butyrate
hydrolysis, it retained less than 50% of the initial activity, while Novozyme 435 retained more than 70% after the tenth cycle.
However, in the synthesis of butyl butyrate, CALB immobilized on coconut fiber showed a good operational stability when compared
to Novozyme 435, retaining 80% of its initial activity after the sixth cycle of reaction. 相似文献
126.
A phosphotyrosine-imprinted polymer receptor for the recognition of tyrosine phosphorylated peptides
Emgenbroich M Borrelli C Shinde S Lazraq I Vilela F Hall AJ Oxelbark J De Lorenzi E Courtois J Simanova A Verhage J Irgum K Karim K Sellergren B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(31):9516-9529
Hyperphosphorylation at tyrosine is commonly observed in tumor proteomes and, hence, specific phosphoproteins or phosphopeptides could serve as markers useful for cancer diagnostics and therapeutics. The analysis of such targets is, however, a challenging task, because of their commonly low abundance and the lack of robust and effective preconcentration techniques. As a robust alternative to the commonly used immunoaffinity techniques that rely on phosphotyrosine(pTyr)-specific antibodies, we have developed an epitope-imprinting strategy that leads to a synthetic pTyr-selective imprinted polymer receptor. The binding site incorporates two monourea ligands placed by preorganization around a pTyr dianion template. The tight binding site displayed good binding affinities for the pTyr template, in the range of that observed for corresponding antibodies, and a clear preference for pTyr over phosphoserine (pSer). In further analogy to the antibodies, the imprinted polymer was capable of capturing short tyrosine phosphorylated peptides in the presence of an excess of their non-phosphorylated counterparts or peptides phosphorylated at serine. 相似文献
127.
Alina Cristiana Gavriluţ 《Mathematica Slovaca》2008,58(1):43-62
In [GOULD, G. G.: Integration over vector-valued measures, Proc. London Math. Soc. (3) 15, (1965), 193–205], G. G. Gould introduced a type of integral of a bounded, real valued function with respect to a finite
additive set function taking values in a Banach space, integral which is more general than the Lebesgue one. Recently, A.
Precupanu and A. Croitoru gave the generalization, defining a Gould type integral for multimeasures with values in
kc(X), X being a Banach space ([PRECUPANU, A.—CROITORU, A.: A Gould type integral with respect to a multimeasure, I, An. Ştiinţ. Univ. “Al. I. Cuza” Iaşi Secţ. I a Mat. 48 (2002), 165–200]). Taking as starting point this work and [PRECUPANU, A.—CROITORU, A.: A Gould type integral with respect to a multimeasure, II, An. Ştiinţ. Univ. “Al. I. Cuza” Iaşi Secţ. I a Mat. 49 (2003), 183–207], we define here the notion of a Gould type integral with respect to a
bf(X)-valued multisubmeasure, pointing out important properties of it. We also establish that, even if we deal with multisubmeasures,
the integral is still a multimeasure.
相似文献
128.
Thaylan Pinheiro Araújo Jordi Morales-Vidal Dr. Georgios Giannakakis Dr. Cecilia Mondelli Henrik Eliasson Prof. Rolf Erni Dr. Joseph A. Stewart Dr. Sharon Mitchell Prof. Núria López Prof. Javier Pérez-Ramírez 《Angewandte Chemie (International ed. in English)》2023,62(42):e202306563
Ternary Pd-In2O3/ZrO2 catalysts exhibit technological potential for CO2-based methanol synthesis, but developing scalable systems and comprehending complex dynamic behaviors of the active phase, promoter, and carrier are key for achieving high productivity. Here, we show that the structure of Pd-In2O3/ZrO2 systems prepared by wet impregnation evolves under CO2 hydrogenation conditions into a selective and stable architecture, independent of the order of addition of Pd and In phases on the zirconia carrier. Detailed operando characterization and simulations reveal a rapid restructuring driven by the metal-metal oxide interaction energetics. The proximity of InPdx alloy particles decorated by InOx layers in the resulting architecture prevents performance losses associated with Pd sintering. The findings highlight the crucial role of reaction-induced restructuring in complex CO2 hydrogenation catalysts and offer insights into the optimal integration of acid-base and redox functions for practical implementation. 相似文献
129.
Sartori T Seigi Murakami F Pinheiro Cruz A Machado de Campos A 《Journal of chromatographic science》2008,46(6):505-509
A rapid and effective isocratic chromatographic procedure is successfully developed to determinate methotrexate (MTX) entrapment efficiency (EE) in polymeric nanocapsules using reversed-phase high-performance liquid chromatography. The method employed a RP-C(18) Shimadzu Shim-pack CLC-ODS (150 mm x 4.6 mm, 5 microm) column with mobile phase constituted by a mixture of water-acetonitrile-tetrahydrofuran (65:30:5 v/v/v; pH 3.0) at a flow rate of 0.8 mL/min. The eluate is monitored with a UV detector set at 313 nm. The parameters used in the validation process are: linearity, specificity, precision, accuracy, and limit of quantitation (LOQ). The linearity is evaluated by a calibration curve in the concentration range of 10-50 microg/mL and presented a correlation coefficient of 0.9998. The polymers (PLA or PLA-PEG), oil, and surfactants used in the nanocapsule formulation did not interfere with analysis and the recovery was quantitative. The intra and inter-day assay relative standard deviation were less than 0.72%. Results are satisfactory, and the method proved to be adequate for the determination of methotrexate in nanocapsules formulations. 相似文献
130.
Antonio C Pinheiro C Chaves MM Ricardo CP Ortuño MF Thomas-Oates J 《Journal of chromatography. A》2008,1187(1-2):111-118
This work reports the development and application of a negative ion mode online LC-ESI-MS method for studying the effect of water deficit on the carbohydrate content of Lupinus albus stems, using a porous graphitic carbon (PGC) stationary phase and an ion trap mass spectrometer. Using this method, separation and detection of several water soluble carbohydrates, ranging from mono-, di-, and oligosaccharides (raffinose, stachyose, and verbascose) to sugar alcohols was achieved in approximately 10 min. This on-line PGC-LC-ESI-MS method shows good linearity with correlation coefficients R(2)>0.99, selectivity, short analysis time, and limits of detection (LOD) ranging from 0.4 to 9 pmol for sugars and 4-20 pmol for sugar alcohols. This PGC-LC-ESI-MS method is sensitive and allowed us to detect even small alterations in carbohydrate levels in L. albus stems that resulted from a mild/early water deficit (nmol g(-1)DW). This paper describes details of our method and its application to the quantitative analysis of water soluble underivatised carbohydrates extracted from L. albus stem tissues that have been subjected to early and severe water deficit conditions, followed by a rewatering period. 相似文献